the advantages of an inline engine are they are cost afective they are a lot cheaper to manafacture, also they are easy to balance making wieght distribution a lot more even, they are a lot easier to work on becouse the majority of engine parts are at the top of the cylinder eg: spark plugs, cylinder head ,head gasket and many more.
the disadvantages are that you cant fit as amny cylinders in a row becouse there is limited space, there is a higher center of gravity and there is a struggle for loner strokes.